Peptide-functionalized nanoparticles (NPs) often rely on a well-defined peptide structure to function. Here, we report the attachment of model peptides to the ligand shell of AuNPs passivated with oligoethylene glycol (OEG). Specifically, peptides containing the repeating (LLKK)_n motif plus either one or two reactive functional groups were covalently linked to OEG-capped, ∼5 nm AuNPs via the Cu⁺-catalyzed azide–alkyne cycloaddition reaction. This work builds on a previous study from our group in which an (LLKK)_n peptide having two reactive functional groups was considered. Peptide attachment was confirmed by FTIR spectroscopy. Amino acid analysis was used to determine that 3–4 peptides were immobilized per AuNP. Circular dichroism spectroscopy revealed a structural change from random coil in solution to α-helical upon attachment to OEG-capped AuNPs. The key result of this study is that the nature of the capping layer on the AuNP surface influences peptide structure to a significant degree. Other important findings resulting from this work are that the AuNP–peptide conjugates reported here are water soluble and that the long axis of the helical peptides is oriented tangent to the AuNP surface. The latter point is important for applications involving biorecognition.

中文翻译：

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寡聚乙二醇封端的AuNP与附着的肽控制肽结构之间的相互作用

肽官能化的纳米颗粒（NPs）通常依赖于定义明确的肽结构来发挥作用。在这里，我们报告模型肽附着到寡聚乙二醇（OEG）钝化的AuNPs的配体壳。特别是，含有重复（LLKK）_n基序加上一个或两个反应性官能团的肽通过Cu ⁺催化的叠氮化物-炔烃环加成反应共价连接到OEG封端的〜5 nm AuNPs 。这项工作建立在我们小组以前的研究，其中（LLKK）_ñ考虑具有两个反应性官能团的肽。肽附着通过FTIR光谱法确认。氨基酸分析用于确定每个AuNP固定有3-4个肽段。圆二色性光谱显示，在附着到OEG封端的AuNPs上，溶液的结构从溶液中的无规卷曲变为α螺旋。这项研究的关键结果是，AuNP表面上覆盖层的性质在很大程度上影响了肽的结构。这项工作得出的其他重要发现是，此处报道的AuNP-肽共轭物是水溶性的，螺旋肽的长轴与AuNP表面相切。后一点对于涉及生物识别的应用很重要。